util/compatfd.c

   1 /*
   2  * signalfd/eventfd compatibility
   3  *
   4  * Copyright IBM, Corp. 2008
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  * Contributions after 2012-01-13 are licensed under the terms of the
  13  * GNU GPL, version 2 or (at your option) any later version.
  14  */
  15
  16 #include "qemu/osdep.h"
  17 #include "qemu/thread.h"
  18
  19 #if defined(CONFIG_SIGNALFD)
  20 #include <sys/signalfd.h>
  21 #endif
  22
  23 struct sigfd_compat_info {
  24     sigset_t mask;
  25     int fd;
  26 };
  27
  28 static void *sigwait_compat(void *opaque)
  29 {
  30     struct sigfd_compat_info *info = opaque;
  31
  32     while (1) {
  33         int sig;
  34         int err;
  35
  36         err = sigwait(&info->mask, &sig);
  37         if (err != 0) {
  38             if (errno == EINTR) {
  39                 continue;
  40             } else {
  41                 return NULL;
  42             }
  43         } else {
  44             struct qemu_signalfd_siginfo buffer;
  45             memset(&buffer, 0, sizeof(buffer));
  46             buffer.ssi_signo = sig;
  47
  48             if (qemu_write_full(info->fd, &buffer, sizeof(buffer)) != sizeof(buffer)) {
  49                 return NULL;
  50             }
  51         }
  52     }
  53 }
  54
  55 static int qemu_signalfd_compat(const sigset_t *mask)
  56 {
  57     struct sigfd_compat_info *info;
  58     QemuThread thread;
  59     int fds[2];
  60
  61     info = g_malloc(sizeof(*info));
  62
  63     if (pipe(fds) == -1) {
  64         g_free(info);
  65         return -1;
  66     }
  67
  68     qemu_set_cloexec(fds[0]);
  69     qemu_set_cloexec(fds[1]);
  70
  71     memcpy(&info->mask, mask, sizeof(*mask));
  72     info->fd = fds[1];
  73
  74     qemu_thread_create(&thread, "signalfd_compat", sigwait_compat, info,
  75                        QEMU_THREAD_DETACHED);
  76
  77     return fds[0];
  78 }
  79
  80 int qemu_signalfd(const sigset_t *mask)
  81 {
  82 #if defined(CONFIG_SIGNALFD)
  83     int ret;
  84
  85     ret = signalfd(-1, mask, SFD_CLOEXEC);
  86     if (ret != -1) {
  87         return ret;
  88     }
  89 #endif
  90
  91     return qemu_signalfd_compat(mask);
  92 }